Glaucoma is a leading cause of irreversible blindness and disability. The disease can remain relatively asymptomatic until late stages and, therefore, early detection and monitoring of functional damage is paramount to prevent functional impairment and blindness. Detection of functional loss in the disease has traditionally been made using standard automated perimetry (SAP). However, SAP testing is limited by the complexity of the examination, subjectivity of patient responses, large variability, cost, and lack of portability. The overall goal of this proposal is to address limitations of currently available techniques by developing a portable objective method for assessment of visual field loss in glaucoma. The investigations of this proposal will address the following 3 specific aims: 1) To develop a portable, objective, multifocal steady state (mfSSVEP)-based visual field assessment platform, integrating a wearable, wireless dry EEG system and a head-mounted display; 2) To develop and validate an Electrooculogram (EOG)-guided method to assess eye- gaze during testing with the envisioned portable platform and 3) To evaluate the reproducibility of the envisioned platform and to conduct preliminary studies evaluating its ability to detect visual fiel loss in patients with glaucoma compared to healthy control subjects. In Specific Aim 1, we will develop a prototype portable device integrating a dry-electrode EEG platform to a cell phone-based head-mounted display for stimulus presentation. We have used similar technology for recent development of brain-computer interfaces, with wireless SSVEP data acquisition and processing. In our preliminary investigation, we have also shown the feasibility of using mfSSVEP for assessment of visual field loss. In the current investigation, advanced signal processing methods will be used to improve signal-to-noise ratio of mfSSVEP from high-density recording. Exploratory studies will be conducted by varying test parameters until a stable testing platform is achieved. In Specific Aim 2, we will integrate an EOG method to the portable plataform, in order to identify fixation losses and allow identification of unreliable mfSSVEP signals to be removed from further analyses. Appropriate eye fixation is essential in order to ensure matching of SSVEP signals to corresponding visual field locations. We will conduct experiments to assess whether the EOG method to filter out unreliable signals improves the accuracy of mfSSVEP to detect visual field losses. In Specific Aim 3, we will conduct validating studies evaluating the reproducibility of measurements obtained with the proposed device, as well as its accuracy for detecting visual field loss in patients with glaucoma. A validated, portable, objective method for assessment of visual field loss in glaucoma may potentially improve screening, diagnosis and detection of glaucoma progression and reduce rates of functional impairment and blindness from the disease.